The team building the app has come from acquisitions of other location apps, like Glancee and Gowalla, as well as a hire from Google, Peter Deng, according to Bloomberg.

Unlike Foursquare, which requires users to announce their location by checking in at a venue in the app, Facebook's forthcoming app may share location with friends without requiring people to take action.

Apple's Find My Friends app and Google's Latitude app for Android smartphones work similarly, but are crippled by their requirement that users laboriously build their friend lists from scratch.

Highlight, a mobile app made by a startup, Math Camp, integrates with Facebook and has attracted a small following among Silicon Valley insiders.

Facebook recently added features for finding local businesses to the Nearby section of its mobile app. Allowing users to locate friends would complete its location features.

Breaking out location functions into a separate app would also follow a pattern Facebook has set with Facebook Messenger, a messaging app which has proven very popular, and Facebook Camera, a less-popular photo-sharing and -viewing app which has been overshadowed by Facebook's Instagram acquisition.